Rapid Northward Expansion of the Blacklegged Tick, Ixodes scapularis, in Response to Climate Change
Our ensembles (AUC: 0.9565 ± 0.0065; TSS: 0.8435 ± 0.0155; Kappa: 0.819 ± 0.014) identified temperature, precipitation, biomass production (NPP), length of the growing season, climate moisture index, and number of yearly degree days as the variables that best explained I. scapularis distribution. Further changes to these climate conditions will result in continued I. scapularis range expansion, with, at the highest estimate, an increased niche area of ~248% (447,532 km2 to 1,556,760 km2) and, at the lowest estimate, by ~205% (409,475 km2 to 1,247,689 km2) before the turn of the century. These distributional niche changes coincide with a northern latitude limit reaching as far as ~48° N by 2040, ~50° N by 2070, and ~52° N by 2100. These findings highlight the invasive potential of I. scapularis, with implications for public health and changing ecosystem dynamics.